The University of Pennsylvania (UP) is a member of the Radiation Therapy Oncology Group (RTOG). It not only contributes large numbers of patients, especially those with head and neck tumors, but both radiation therapy and non-radiation therapy specialists contribute time and effort in committee work and in providing consultative services. Thus, the University of Pennsylvania exemplifies in its activities a commitment to the interdisciplinary approach to patients with oncological diseases and assists RTOG, a cooperative group of radiation therapy research and clinical centers, in the conduct of joint clinical investigation. The group conducts randomized clinical trials and other cooperative clinical studies to advance knowledge in the cure and control of cancer by gathering adequate numbers of patients necessary for the answer to important clinical questions. It also makes possible the collection of long-term data with regard to radiation complications and patient survival, and promotes multi-disciplinary care by integrating its study programs with those of other disciplines. In that way, it also enriches training programs in oncology as well as radiation therapy.